S
M
T
W
T
F
S
30
90°
77°
31
89°
76°
1
90°
75°
2
89°
77°
3
90°
76°
4
90°
76°
5
90°
76°
6
90°
76°
7
90°
76°
8
90°
77°
9
Hist. Avg.
89°
77°
10
Hist. Avg.
89°
77°
11
Hist. Avg.
89°
77°
12
Hist. Avg.
89°
77°
13
Hist. Avg.
89°
77°
14
Hist. Avg.
89°
77°
15
Hist. Avg.
89°
77°
16
Hist. Avg.
89°
77°
17
Hist. Avg.
89°
77°
18
Hist. Avg.
89°
77°
19
Hist. Avg.
89°
77°
20
Hist. Avg.
89°
77°
21
Hist. Avg.
89°
77°
22
Hist. Avg.
89°
77°
23
Hist. Avg.
89°
77°
24
Hist. Avg.
89°
77°
25
Hist. Avg.
89°
77°
26
Hist. Avg.
89°
77°
27
Hist. Avg.
89°
77°
28
Hist. Avg.
88°
77°
29
Hist. Avg.
88°
77°
30
Hist. Avg.
88°
76°
1
Hist. Avg.
88°
76°
2
Hist. Avg.
88°
76°
3
Hist. Avg.
88°
76°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in San Juan
San Juan's September 2026 forecast shows daily high temperatures ranging from 89° to 90°, with overnight lows between 75° and 77°. The average high for September is 90° with an average low of 76°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how September weather will actually feel in San Juan. See also: October | November | December.
